1. Field of the Invention
This invention relates to a light-filtering apparatus, in particular for a dental lamp.
2. Description of the Related Art
One of the problems that exists in the modern dental office occurs while working with light-cured composite resins under a standard operatory light. Light-cured composites have been one of the greatest advancements in modern dentistry because they allow the dentist easy placement of tooth-colored fillings in teeth. However, the one characteristic that makes such composites so versatile and workable, i.e. their ability to set up and be cured when illuminated by a 350 to 550 (usually 400 to 500) nanometer (nm) wavelength of light, also makes the composites vulnerable to premature hardening by the standard operatory light.
To cope with this problem, the dentist must either work very quickly or turn the operatory light away from the tooth where the composite is being placed. Neither choice is ideal for a quality dental procedure because working quickly may result in mistakes, such as leaving voids. Likewise, by turning the light away to stop the curing process, the dentist has a difficult time seeing what he or she is doing, especially in the placement of posterior composites.
One way to solve the problem is to develop composites which take longer to cure. A simpler way to solve the problem is to filter out the 350-550 nm wavelength that is emitted from the operatory light. By doing so, the dentist can work at a normal pace and still have almost 90% illumination on the subject tooth.
One such solution was proposed by Dr. Theodore P. Croll of Doylestown, Pa., in his U.S. Pat. No. 4,640,685 which issued to him on Feb. 3, 1987, for a hand-held light-filtering paddle. His invention is intended to protect the dentist's eyes from the light wavelength emitted by the light-curing gun. However, the disadvantage of this device is that the dentist is left with only one free hand to work.
Dr. Croll shortly thereafter obtained U.S. Pat. No. 4,662,842 which issued to him on May 5, 1987, for a finger-mounted light filter. Again, the filter is intended to protect the dentist's eyes from the curing light. However, while permitting the free use of both hands, the dentist is unable to reach into the patient's mouth with the filter secured on one finger.
Drs. Cunningham and Leggo of Australia later obtained U.S. Pat. No. 5,509,800 which was granted on Apr. 23, 1996, for a filter which is detachably fitted in front of a dental lamp by an attachment device. Because their filter attaches to the actual light housing itself, it is difficult, if not impossible, to attach the filter to most lights. However, the main drawback of this development is that the filter must be handled each time when it is used and it must be placed somewhere when it is not in use. Thus, a new problem of cross contamination between patients and staff members is created.
Thus, it remains a problem in the prior art to provide a dental filter which permits the dentist to have free use of both hands and which simultaneously prevents cross contamination between patients and staff members.